Cardiovascular disease frequently arises from the accumulation of atheromatous deposits on inner walls of vascular lumen, particularly the arterial lumen of the coronary and other vasculature, resulting in a condition known as atherosclerosis. These deposits can have widely varying properties, with some deposits being relatively soft and others being fibrous and/or calcified. In the latter case, the deposits are frequently referred to as plaque. These deposits can restrict blood flow, which in severe cases can lead to myocardial infarction.
The assessment and treatment of cardiovascular disease often involves imaging the inside of the vessel. This is often performed with an imaging catheter that is inserted into a blood vessel or chamber of the heart in order to diagnose or treat certain conditions. Conventional imaging methods only permit to a large extent the imaging of objects and surfaces located along the sides of catheter. For example, catheters that use piezoelectric transducers for imaging typically employ the transducers at forty-five degree angles to provide conical views.
These limitations of conventional devices can be problematic when it is necessary to image an object directly in front of the catheter rather than along the sides. For example, an artery may be completely blocked with plaque, in what is referred to as a chronic total occlusion. Chronic total occlusions or CTOs are responsible for clinically significant decreases in blood flow. In addition, CTOs often mean more significant intervention, such as coronary artery bypass surgery. Accordingly, the ability to quickly and accurately identify and assess CTOs is vital to the management of cardiovascular disease.